Dissolution of cobalt ferrites by thioglycolic acid
Abstract
The dissolution of cobalt ferrites CoxFe3–xO4 by thioglycolic acid involves the chemisorption of thioglycolate anion onto FeIII ions of the solid, followed by an electron transfer from the ligand to the metal ion and subsequent release of FeII. Kinetic data suggest that two adjacent FeIII–L sites evolve to two FeII+L2. Substitution of CoII for FeII does not bring about any noticeable change in the kinetics for x < 0.6. For larger values of x, the early mechanism of dissolution changes, suggesting that electron hopping within the octahedral sites may produce a chain dissolution of FeII for each single original electron transfer from thioglycolate. Rate data in the presence of exogenous FeII are also discussed.